From C to GMP implementation

Question

I would ask you how this code written in c would look in GMP. I tried something to write but the library is hard to understand. I don't know how to write operation: r = r*10 + n%10; in gmp. I would be very grateful for help.

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <gmp.h>

long long rev(long long n)
{
    long long r = 0;
    while (n > 0)
    {
        r = r*10 + n%10;
        n = n/10;
    }
    return r;
}

bool palindrome(long long n)
{
    return (rev(n) == n);
}

void reverseAdd(long long n)
{
    long long r=0;
    while (n <= 100000000000000)
    {
        r = rev(n);
        printf("stage: %lld + %lld\n",n,r); 

        n = n + r;

        if (palindrome(n))
        {
            printf("Palindrom: %lld\n",n);
            break;
        }
        else if (n > 100000000000000)
        {
            printf("Not a palindrome\n");
        }
    }
}


int main()
{
    long long l;

    printf("Give the number to analyze:");
    scanf("%lld",&l);
    reverseAdd(l);
    return 0;
}

Answer 1

To print mpz_t variables use gmp_printf. GMP adds types ‘Z’, ‘Q’ and ‘F’ for mpz_t, mpq_t and mpf_t respectively.

The GMP types are:

F   mpf_t, float conversions
Q   mpq_t, integer conversions
M   mp_limb_t, integer conversions
N   mp_limb_t array, integer conversions
Z   mpz_t, integer conversions

gmp_printf accepts format strings similar to the standard C printf (see Formatted Output in The GNU C Library Reference Manual).

Referring to your last question and your posted program, you can use gmp_printf to print l. See the program modified below:

//....

int main()
{
   int k;
    mpz_t l;
    mpz_t n;
    mpz_init (n);  /* remember to init mpz variables */
    mpz_init (l);

    printf("Number to analysis: ");
    gmp_scanf("%Zd",l);

    gmp_printf ("%s the mpz number %Zd\n", "You have entered", l);

    do
    {
        mpz_set(n, l);
        analyzeAdd(n);
        mpz_add_ui(l,l,1);

     }while(false);

    gmp_printf ("%s is equal %Zd\n", "Now the n", n);

    return 0;
}

Output:

Number to analysis: 123321
You have entered the mpz number 123321
Now the n is equal 246642